The study of vocal development has revealed salient differences in vocalizations of profoundly and severely-to-profoundly hearing impaired infants compared with their normally hearing counterparts. Since the differences are clear, and many parents can recognize the relevant vocal features when their infants produce them, it seems likely that a cost- effective hearing screening method (for profound or severe-to-profound impairments) could be based upon parent interviews that might be conducted by telephone, either with or without a prior brief training session on recognizing the relevant vocal features. The proposed study would evaluate in detail various possible vocal measures that might make it possible to identify not only profound and severe-to-profound impairments, but also lesser hearing losses and other speech-related disorders. In addition the study would systematically evaluate the reliability of parent reports on the relevant vocal features both with and without brief training in recognizing vocal sounds of infants. In particular, it is of concern to evaluate the accuracy of reports provided by parents from varying degrees of socio-economic status. The resulting information will contribute to development of a cost- effective battery of screening instruments, and a deeper understanding of infant vocalizations as precursors to a speech capacity.